Dehumidifying breather system for mobile cargo container



H. I. KRELLEN 3 ,271,089

DEHUMIDIFYING BREATHER SYSTEM FOR MOBILE CARGO CONTAINER Sept. 6, 1966 6 Sheets-Sheet 1;

Filed Oct. 29, 196

INVENTOR. HARRY I. KRELJLEN BY 74 Sept. 6, 1966 H. x. KRELLEN 3,271,089

DEHUMIDIFYING BREATHER SYSTEM FOR MOBILE CARGO CONTAINER Filed Oct. 29, 1965 6 Sheets-Sheet 2 INVENTOR.

HARRY I. KRELLEN T1 (E a/@1554 BM CM";

H. l. KRELLEN Sept. 6, 1966 DEHUMIDIFYING BREATHER SYSTEM FOR MOBILE CARGO CONTAINER 6 Sheets-Sheet '5 Filed Oct. 29, 1963 INVENTOR.

HARRY I. KAELLEN BY. Kai? WV LW.

H. 1. KRELLEN 3,271,089

DEHUMIDIFYING BREATHER SYSTEM FOR MOBILE CARGO CONTAINER Sept. 6, 1966 6 Sheets-$heet 4 Filed Oct. 29, 1963 INVENTOR.

HARRY I. KRELLEH 7 6. L I 16 @z/j Q.4/. Cfln H. I. KRELLEN Sept. 6, 1966 DEHUMIDIFYING BREATHER SYSTEM FOR MOBILE CARGO CONTAINER 6 Sheets-Sheet 5 Filed Oct. 29, 1963 INVENTOR.

' HARRY I. KAELLEA/ H m a e. may H. wx mwflg Sept. 6, 1966 H, 1. KR L 3,271,089

DEHUMIDIFYING BREATHER SYSTEM FOR MOBILE CARGO CONTAINER Filed 001:. 29, 1963 6 Sheets-Sheet 6 IHIM -22 F5 12}; E INVENTOR.

HARRY I. KRELLEN United States Patent 3,271,089 DEHUMIDIFYING BREATHER SYSTEM FOR MOBILE CARGO CONTAINER Harry I. Krellen, Newport News, Va., assignor to the United States of America as represented by the Secretary of the Army Filed Oct. 29, 1963, Ser. No. 319,896 1 Claim. (Cl. 312-313) The invention described herein may be manufactured and used by or for the Government for governmental purposes without =the payment to me of any royalty thereon.

This application is a continuation-in-p-art of my earlier application Serial No. 137,704, filed September 12, 1961, for Dehumidifying Breather System for Mobile Cargo Container, now abandoned in favor of the present application.

This invention relates to reusable cargo containers or boxes and particularly to the container developed by the military for overseas shipment of supplies and equipment and designated the CONEX Container. Although these containers have been in use for a number of years, they are still undergoing tests, modifications, and improvement. A recent research and development effort has been made in the direction of providing a substantially moisture fi'ee container for shipment and storage of goods subject to damage by moisture. This required completely sealing the container against passage of air through its walls but, because of the large areas of the top, bottom, and sides of the container and the construction of the container, it was found necessary to permit the interior of the container to breathe incident to variations in atmospheric pressure and temperature in order to maintain pressures inside and outside of the container substantially equal. Since this breathing action had a tendency to draw moist air into the container where the moisture had a tendency to condense, it was also found necessary to remove a major portion of the moisture from the air drawn into the container by the breathing action.

It is, therefore, among the objects of the invention to provide an improved cargo container of the character indicated having its interior effectively sealed against leakage of air either into or out of the container and having an especially arranged breathing apparatus for substantially. equalizing atmospheric pressure inside and outside of the container.

A further object resides in the provision in a cargo container, of breathing apparatus effective to remove most of the moisture content from air breathed or inhaled into the container.

A still further object resides in the provision, in a cargo container, of improved breathing apparatus including a desiccant receptacle or cartridge which can be readily removed and replaced without breaking the container seal or disturbing the contents of the container, and air passage tubes or conduits leading to the desiccant cartridge which conduits are effective to remove from air inhaled into the container through the desiccant a large portion of the moisture content of such air to thereby reduce the rate of deterioration of the desiccant material.

An additional object resides in the provision in a cargo container, of improved breathing apparatus arranged to adjust the air pressure inside a container to the external pressures at the windward and leeward sides of a container subjected to a high relative wind as by standing in the open during a storm or being transported at high speed on an open vehicle.

Yet another object resides in the provision of breathing apparatus for a CONEX Container of known or conventional construction which apparatus can be installed without any material modification to the container structure and without taking up an undesirable amount of cargo space within the container.

Other objects and advantages will become apparent from a consideration of the following description and the appended claims in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view of a CONEX Container of known or conventional construction with a portion broken away to show the application thereto of breather apparatus illustrative of the invention;

FIG. 2 is a front elevational view of a portion of the breather apparatus shown in FIG. 1;

FIG. 3 is a fragmentary cross-sectional view substantially on a plane indicated by the line 3-3 on FIG. 2;

FIG. 4 is an elevational view of the door or access end of the container;

FIG. 5 is a fragmentary cross-sectional view substantially on a plane indicated by the line 5-5 on FIG. 4;

FIG. 6 is a fragmentary cross-sectional View substantially on a plane indicated by the line 66 on FIG. 1; and

FIG. 7 is a fragmentary cross-sectional view substantially on a plane indicated by the line 7-7 on FIG. 3.

With continued reference to the drawings, the CONEX Container shown in FIG. 1 is a reinforced metal box of rectangular shape mounted on a pair of skids, as indicated at 10, extending one along each side of the box at the bottom thereof. These skids support the bottom of the container above the associated floor or the ground and are provided with openings and recesses through which the fingers of a fork-lift truck can be inserted for raising and moving the container. A group of these containers have been standardized at 5,000 pound load capacity and this is the type of container generally under consideration in this description although the dehumidifying apparatus to be hereinafter described, can be used with containers and boxes of various sizes, shapes, and capacities.

The container, as illustrated, has corner posts, indicated at 11, 12, and 13 in FIG. 1, bottom frame members, as indicated at 14, extending between the lower ends of adjacent corner posts, and top frame members, as indicated at 15, extending between the top ends of the corner posts. The walls of the container are shown as formed of deeply corrugated metal end plates 16 and side plates 17 extending between corresponding corner posts, and upper and lower frame members. The corrugations are shown as being of rectangular shape and extending vertically along the walls of the container where they act to stiffen the wall plates and materially reinforcethe container structure. These corrugated side and end plates are usually covered on their inner surfaces with flat metal plates, secured to the corrugated plates by suitable means, such as spot Welding, and the top wall of the container may have a flat metal plate on the outer as well as the inner side of the corrugated wall in order to provide a flat surface for stacking containers and for other purposes. The bottom of the container is usually formed by a relatively heavy framework extending between the skids 10 with a heavy gauge metal plate overlying this framework. As the container construction is only incidental to the present invention, it is believed that the above description is sufficient for the purposes of the present disclosure.

Since in the construction of CONEX Containers by usual industrial methods, a large number of small holes, cracks, and other openings are left in the container walls and along the lines where contiguous walls are joined together, where a dehumidified container is desired, it has been found necessary to spray the entire interior of the container with a suitable material, such as a plastic or bituminous material, in order to close all of these openings. In some cases, after the interior surfaces have been sprayed, they are covered with a suitable lining material such as a metal foil backed with woven fabric to provide a clean interior surface the material of which will not adhere to or rub off onto goods placed in the container.

One of the major sources of air leakage of the CON- EX Containers has been the access door provided in one end of a container. Many arrangements have been tested for reducing or eliminating this source of air leakage and one of the most successful of such arrangements is illustrated in FIGS. 4 and 5. In this case, the usual door may be left in place or may be removed, as may be desired. Within the normal doorway a bulkhead is constructed in the end of the container, this bulkhead being firmly secured, as by welding, to the adjacent corner post structures and the top and bottom frame structures of the end of the container. The bulkhead is provided with a rectangular opening 21, preferably having rounded corners, and a flange 22 surrounds this opening and extends perpendicularly from the bulkhead wall 20. When the container is closed, a flat closure plate 23 of the same shape but somewhat larger than the opening 21 overlies the opening and extends marginally a substantially uniform distance beyond the outer edge of the flange 22. This closure plate carries on its side adjacent to the flange 22 a marginal sealing strip 24 of a compressible material, such as rubber, and this sealing strip bears against the rounded outer edge of the flange to provide an airtight seal between the cover plate 23 and the bulkhead 20. Double eye members 25 are secured to the bulkhead 20 adjacent the flange 22 but outside of the marginal edge of the cover plate 23 and eye bolts 26 are pivotally secured to the eyes 25 by pivot pins 27 extending through aligned apertures in the eye member 25 and eye bolt 26. Notched angle brackets 28 are secured to and marginally overhang the closure plate 23 in position for corresponding eye bolts 26 to be received in the notches of the angle brackets and nuts 29, threaded onto the screw threaded shank portions of the eye bolts, force the closure plate 23 inwardly to compress the sealing strip 24 against the outer edge of the bulkhead flange 22 to provide an airtight closure for the access opening of the container.

The above described closure for the access opening of the container together with the lining applied to the interior of the container renders the interior of the container substantially airtight and this would be an ideal condition for maintaining the air within the container substantially moisture free since it would be necessary only to include in the container a quantity of desiccant material sufficient to absorb the moisture initially in the air trapped in the container. It has been found, however, as explained above, that a container of the size to which the invention is applied does not successfully withstand extreme variation in the difference in the air or atmospheric pressure within and outside of the container. For example, if a side wall of the container is approximately 10 feet square, the area would be 100 square feet or 14,400 square inches. A difference of one-half pound in the pressure inside and outside of the container would thus exert a pressure of 7,200 pounds on the container wall. This is sufficient pressure to cause the wall to bulge, either inwardly or outwardly depending on the direction of the pressure gradient, with possible damage to the wall and to its marginal connection to the container frame. When the container is subjected to a relative wind of high velocity, the positive atmospheric pressure outside of the container at the windward side and the negative pressure gradient across the container wall at the leeward side can be sufficient to cause serious deformation of these container walls. For these reasons, it has not only been found necessary to provide means to permit the interior of the container to breathe to thereby substantially equalize the pressure of the air inside and outside of the container but also to permit such breathing to take place through all four vertical for the interior of the container, the end wall of the container opposite the wall containing the access opening 21 is cut away to provide a small opening 30 of rectangular shape at one upper corner of the end wall 16, as shown in FIG. 1. A ledge member 31 of channel shaped cross-section is placed on the edge of the container wall at the bottom side of the opening 30 to cover the exposed ends of the corrugations and a rectangular plate 32, FIG. 2, is set into the opening 30 and secured to the edges of the container wall along the sides of the opening 30 to provide an airtight closure for the opening. As shown in FIG. 3, this plate is provided with off-set marginal flanges, as indicated at 33, which overlie the edge portions of the container wall 16 surrounding the opening 30 and are secured to the wall by suitable means, such as weld ing. The plate 32 is provided with a circular opening 34 surrounded interiorly of the plate by a flat ring 35 spaced from the plate by a gasket 36 of suitable compressible material. A cylindrical casing wall 37 is secured at one end to the inner side of thering 35 and extends perpendicularly from this ring into the interior of the container to provide a housing for a cylindrical desiccant cartridge presently to be described.

The rear or inner wall of the portion of the receptacle 37 is supported by a suitable bracket 38 secured to a structural element 39 of the container.

The receptacle 37 is open at both ends and slidably receives the desiccant cartridge or canister, generally indicated at 40. This canister has a cylindrical wall 41 and perforated end walls 42 and 43 secured in the cylindrical wall and disposed perpendicularly thereto. The rear end wall 42 is disposed near the rear or inner end of the canister wall 41 and the front wall 43 is spaced from the front end of the canister wall to provide a plenum chamber 44 within the canister which chamber communicates through suitable openings in the canister wall with the interior of the receptacle. The space within the canister wall 41 between the perforated end walls 42 and 43 is filled with a body of desiccating material such. as silica gel, calcium chloride or other suitable material. It will be noted that the cylindrical canister wall 41 is slidable through the opening in the flat ring 35 and fits this opening with sufficient accuracy that the flat ring maintains the cylindrical canister Wall annularly spaced at a substantially uniform distance from the cylindrical container wall 37.

At its front end, the canister wall 41 is secured to a flat ring 45 and extends perpendicularly from this ring. The ring 45 extends both inwardly and outwardly of the canister wall 41 and its outwardly extending portion overlies the flat ring 35 at the side of plate 32 remote from ring 35 and is spaced from the plate 32 by an annular gasket 46 of suitable sealing material. A circular cover plate 47 overlies the ring 45 at the side of the latter remote from the canister wall 41 and is spaced from the ring 45 by an annular gasket 48 of suitable sealing material. The rings 35 and 45, the supporting plate 32 and the cover plate 47 and the gaskets 36, 46, and 48 are all provided with aligned apertures angularly spaced at sub stantially uniform distances around the ring and the circular opening in the plate 32 and suitable bolts 50 extend through these openings and receive nuts 51 at the outer side of the cover plate 47 to firmly secure the assembly together and to the supporting plate 32. By removing the bolt nuts 51 and the cover plate 47, the desiccant canister 40 can be pulled out of the receptacle 37 and replaced by another canister, if desired. These canisters are normally so constructed that after a desiccant canister absorbs a sufi'icient amount of moisture to become inefiicient or ineffective, it can be placed in a drying oven and reconditioned to a fully effective condition.

A system of breather tubes is provided comprising 8 tubes all connected at corresponding ends to the wall of the container 37 in the region of the plenum chamber 44. The tubes may be secured to the wall 37 by threaded couplings or by being brazed to suitable reinforcing sleeves or nipples which are in turn brazed to the receptacle wall and each tube communicates with the interior of the receptacle through a suitable opening provided in the receptacle wall as indicated at 54 for the tube 62. Two of the tubes, as indicated at 56 and 57, in FIG. 6, extend through the back wall 16 of the container at loca tions spaced apart near the top of the container, two.

other tubes as indicated at 58 and 59 extend through the side wall 17 of the container, two similar tubes 60 and 61 extend through the side wall opposite the side wall 17 and tubes 62 and 63 extend through the front wall of the container in which the access opening is provided. While the tubes may be of any suitable material and dimensions, it has been found that commercial copper tubing of from one-quarter to one-half inch diameter is easy to install and functions satisfactorily. Condensed moisture is deposited on the inner walls of the tubes and is discharged from the tubes when air is exhaled or breathed out of the container through the tubes. The tubes are so installed that, when the container is resting on a substantially level surface, all of the tubes are inclined downwardly from their connections to the receptacle 37 to the discharge ends of the tubes disposed outside of the container walls so that there will be a tendency for any moisture condensed in the tubes to drain out of the discharge ends and not into the portion of the receptacle 37 to which the tubes are connected. The tubes are individually extended through suitable apertures in the walls of the container and the openings or apertures through which the tubes extend are preferably sealed by suitable grommets of rubber or other sealing material seated in the apertures and closely surrounding the tubes. The outer ends of the tubes are located between the outwardly projecting portions of the wall corrugations and do not extend outwardly of the common outer surface of the corrugations so that the ends of the tubes will not be damaged when containers are loaded or stored side by side in contact with each other. Outside of the container wall, the tube ends are bent downwardly or, if desired, may be provided with downwardly turned elbow fittings to assist in the discharge of moisture from the tubes and to prevent rain or snow from entering the outer ends of the tubes. By removing a large portion of the moisture from the air entering the container as the air passes through the breather tubes, the amount of moisture that must be extracted by the desiccant canister is greatly reduced and the useful life of the canister is so greatly increased that a loaded container may be permitted to stand for a long period of time in storage without the necessity of renewing the desiccant canister. Also, by extending the breather tubes through all four walls of the container, the air pressure within the container is maintained substantially at ambient atmospheric pressure, even when the container is being subjected to a relative wind of high velocity, so that the pressures exerted on the windward and leeward walls of the container are not sufiicient to endanger the structure of these walls.

Operation No condensation will take place in the tubes under some conditions. As exemplary, if the breather tubes are warmer than the dewpoint of the ambient air, such as on a warm day when the relative humidity of the ambient air is very low, no condensation will take place. However,

the tubes are inside of the container and thus are shaded from direct sunlight. Also, at times, the tubes are kept cool by cool winds on the container Walls, cool surrounding objects, or the cool contents of the container. As the container cools still further, as at night, the air inside contracts and air is inhaled through the breather tubes. 'If the exterior ambient air has a high relative humidity it will condense as it strikes the cool tube walls and the condensation will automatically drain down and out through the tubes. This reduces the relative humidity of air entering desiccant canister 40 thereby prolonging the life of the desiccant.

While a suitable mechanical embodiment of the invention has been herein above described and illustrated in the accompanying drawings, it is to be understood that the scope of the invention is in no way limited to the embodiment so described and illustrated but is commensurate with the scope of the appended claim.

I claim:

In combination with a cargo container having four vertical walls one of which is provided with an access opening to the interior of the container, means rendering said container substantially air tight, apparatus providing substantially free breathing between the interior of said container and the ambient atmosphere while maintaining the interior of said container substantially free of moisture comprising a receptacle mounted in said container and opening through one vertical wall thereof, said receptacle including a plenum chamber in one end portion, desiccant material in said receptacle between said plenum chamber and the interior of said container, and a plurality of breather tubes extending from said plenum chamber through the vertical walls of said container, said breather tubes sloping downwardly away from said plenum chamber for gravity flow of condensation therefrom, said tubes passing for substantial distances inside of said container where they are subject to ambient temperatures which, at times, are cool enough to condense moisture from ambient air surrounding said container as it enters said tubes, the arrangement being such that air entering said container from the outside atmosphere passes first through said breather tubes and then through said desiccant material before entering said container.

References Cited by the Examiner UNITED STATES PATENTS 480,718 8/1892 Ennis 9851 633,823 9/1899 Fleming 55387 636,651 11/1899 Fleming 55387 646,276 3/ 1900 Follweiler 98-51 X 1,399,126 12/1921 Kerwien 9851 1,577,867 3/1926 Moyer 55268 1,649,732 11/ 1927 Richmond 31231.3 X 1,850,923 3/1932 Danzer 2196 2,507,028 5/1950 Lockwood 55--387 2,593,132 4/1952 Gannon 55387 X 2,596,763 5/ 1952 Crowley 22223 2,603,308 7/1952 McCall 55387 X 2,741,897 4/1956 Riggins 9851 X 2,789,654 4/ 1957 Zurit 55387 3,064,819 11/1962 Jones 55387 X FOREIGN PATENTS 107,742 6/ 1939 Australia. 1,075,894 2/ 1960 Germany.

335,881 7/ 1935 Italy.

CLAUDE A. LE ROY, Primary Examiner.

FRANK B. SHERRY, Examiner.

A. FRANKEL, Assistant Examiner. 

